Recent content by alialice

I surely refer to a thermodynamic interpretation in what I'm goin to write. I don't agree on the point where you say that degeneracy has no effect on pressure, or that it has only in connection with heat transport. White dwarfs and neutron stars are maintained by degeneracy pressure because they...

Why do you say that? So how do you explain helium flash? After the nuclear explosion the gas is no more degenerate and it expand regularly.

Is there someone how could explain me why is color temperature (Tcol) always greater than the effective temperature (Teff) of a star? I know that Teff is the temperature of the last interaction surface, where photons are emitted. In the case that the scattering opacity is the dominant one...

The two statements are both true. The second one, related to helium flash, can be explained with the concept of thermal stability. If a degenerate system goes under compression, it cools down (it becomes "more degenerate" because density increases). Thermal stability is achieved only by...

Homework Statement \int \sqrt {\frac{1+x}{1-x}} dx = ? The solution is: = \arcsin{x} -\sqrt{1-x^2} + const If someone could help me to find the solution I'll be very pleased! :-) Thanks everybody!

When you write an action and then you calculate its minima, how can you be sure that they are minima and not maxima? Thanks

http://en.wikipedia.org/wiki/Gravitation As a reference you can present this: Wikipedia is a virtual encyclopedia. In the section Earth's gravity it is written explicitly that: Every planetary body (including the Earth) is surrounded by its own gravitational field, which exerts an attractive...

See pages 76-77 of Wald's General Relativity. The first equation, which describes the motion of a particle in the gravitational field phi, can be derived from the second, the geodesic equation for a point particle in a curved spacetime, in the Newtonian limit.

I know that there is the possibility of some objects to interact with CMB. It is the case of high energy electrons that can react with CMB photon through inverse Compton scattering. This leads to a detectable distortion of CMB spectrum. It is a way used to detect clusters of galaxies and the...

About Wald's book: I like Wald's book, but I started studying GR with the help of professor who was very clear in his explanation. He started the course with some differential geometry and than went on. So with the help of my notes, and the Lecture notes on GR by Carrol, that I forgot to...

Yes :)

Thank you. I know that during the inflationary phase, H=Lambda/3, where Lambda is the cosmological constant, and the expansion is exponential. So H is constant. But in Liddle it is said: "During inflation \frac{d\left( H^{-1} /a\right)}{dt}<0 The Hubble length, as measured in comoving...

http://arxiv.org/abs/physics/0311011/ I've just found this notes, try to look at them, even if they are more mathematic than physics. The standard reference for the subject is a book called Classical Electrodynamics by Jackson.

Maxwell theory is relativistic( in the sense of special relativity): it predicts for example that the speed of an electromagnetic wave is c. What are you looking for, I think it is electrodynamics. You can study the motion of particles in electromagnetic field, and for this you need special...

For GR you need some basis of differential geometry. For the second question, I think you refer to Classical Electrodynamics? For it you need vector calculus, and to know something about tensor if you use covariant formalism. Is this what you were asking?